A saccharinate-iron(II) complex with a free saccharin molecule present, [Fe(phen)3]sac2.sacH.6H2O.

The crystal structure of the title compound, tris(1,10-phenanthroline-N,N')iron(II) bis[1,2-benzisothiazol-3(2H)-onate 1,1-dioxide] 1,2-benzisothiazol-3(2H)-one 1,1-dioxide hexahydrate, [Fe(C12H8N2)3](C7H4NO3S)2.C7H5NO3S.6H2O, at 120 K consists of slightly distorted octahedral [Fe(phen)3]2+ cations (phen is 1,10-phenanthroline), two saccharinate anions and a free saccharin molecule, as well as six waters of crystallization. The compound has been confirmed as diamagnetic low-spin iron(II) by magnetic measurements. There is extensive hydrogen bonding leading to a three-dimensional network.